Arteus, Legion's Savior

Flying, first strike, vigilance
When Arteus, Legion's Savior enters the battlefield, if you cast it, destroy all creatures you
don't control unless you pay {x} if X is 5 or more, destroy all creatures instead and create
X 1/1 white and red soldier tokens
with haste. If Arteus Legion's Savior would
die this turn exile it instead.
At the beginning of your end step return it to the battlefield.